libavcodec/tmv.c

   1 /*
   2  * 8088flex TMV video decoder
   3  * Copyright (c) 2009 Daniel Verkamp <daniel at drv.nu>
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * FFmpeg is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with FFmpeg; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 /**
  23  * 8088flex TMV video decoder
  24  * @file libavcodec/tmv.c
  25  * @author Daniel Verkamp
  26  * @sa http://www.oldskool.org/pc/8088_Corruption
  27  */
  28
  29 #include "avcodec.h"
  30
  31 #include "cga_data.h"
  32
  33 typedef struct TMVContext {
  34     AVFrame pic;
  35 } TMVContext;
  36
  37 static int tmv_decode_frame(AVCodecContext *avctx, void *data,
  38                             int *data_size, AVPacket *avpkt)
  39 {
  40     TMVContext *tmv    = avctx->priv_data;
  41     const uint8_t *src = avpkt->data;
  42     uint8_t *dst, *dst_char;
  43     unsigned char_cols = avctx->width >> 3;
  44     unsigned char_rows = avctx->height >> 3;
  45     unsigned x, y, mask, char_y, fg, bg, c;
  46
  47     if (tmv->pic.data[0])
  48         avctx->release_buffer(avctx, &tmv->pic);
  49
  50     if (avctx->get_buffer(avctx, &tmv->pic) < 0) {
  51         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
  52         return -1;
  53     }
  54
  55     if (avpkt->size < 2*char_rows*char_cols) {
  56         av_log(avctx, AV_LOG_ERROR,
  57                "Input buffer too small, truncated sample?\n");
  58         *data_size = 0;
  59         return -1;
  60     }
  61
  62     tmv->pic.pict_type = FF_I_TYPE;
  63     tmv->pic.key_frame = 1;
  64     dst                = tmv->pic.data[0];
  65
  66     tmv->pic.palette_has_changed = 1;
  67     memcpy(tmv->pic.data[1], ff_cga_palette, 16 * 4);
  68
  69     for (y = 0; y < char_rows; y++) {
  70         for (x = 0; x < char_cols; x++) {
  71             c  = *src++ * 8;
  72             bg = *src  >> 4;
  73             fg = *src++ & 0xF;
  74
  75             dst_char = dst + x * 8;
  76             for (char_y = 0; char_y < 8; char_y++) {
  77                 for (mask = 0x80; mask; mask >>= 1) {
  78                     *dst_char++ = ff_cga_font[c + char_y] & mask ? fg : bg;
  79                 }
  80                 dst_char += tmv->pic.linesize[0] - 8;
  81             }
  82         }
  83         dst += tmv->pic.linesize[0] * 8;
  84     }
  85
  86     *data_size = sizeof(AVFrame);
  87     *(AVFrame *)data = tmv->pic;
  88     return avpkt->size;
  89 }
  90
  91 static av_cold int tmv_decode_close(AVCodecContext *avctx)
  92 {
  93     TMVContext *tmv = avctx->priv_data;
  94
  95     if (tmv->pic.data[0])
  96         avctx->release_buffer(avctx, &tmv->pic);
  97
  98     return 0;
  99 }
 100
 101 AVCodec tmv_decoder = {
 102     .name           = "tmv",
 103     .type           = CODEC_TYPE_VIDEO,
 104     .id             = CODEC_ID_TMV,
 105     .priv_data_size = sizeof(TMVContext),
 106     .close          = tmv_decode_close,
 107     .decode         = tmv_decode_frame,
 108     .capabilities   = CODEC_CAP_DR1,
 109     .long_name      = NULL_IF_CONFIG_SMALL("8088flex TMV"),
 110 };